Manufacture of lubricating oil



MANUFACTURE OF LUBRICATING OIL Filed May 4, 1945 A 2 Sheets-Sheet 1 soo l b, oo

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` MANUFACTURE 0F LUBRICATING OIL Filed May 4, 1945 2 sheets-sheet 2 if BY Jay/V f? (wir.

Patented Feb. 8, 1949 liti ITE@ STALES li/ANUFACTURE OF LUBRICATING `OIL Fred vC. Toettcher, Fishkill, and John R. Coley,

Beacon, N. Y., assignors to 'The Texas Gom- 4pany, New York, N. if., a-corpioration of Dela- 4'Claims. i

This invention relates to the-treatment of hy- Vdrocarbon oils to produce lubricating oil highly resistant to oxidation. -rhe invention is conlcernedv with improvements in the treatment of lubricating stocks to effect increase in oxidation stability and to produce oils of highly stable character'adapted or'turbine oils, lubricating oils for internal combustion engines'and the like.

In `accordance with the invention the oil is subjected to catalytic treatment in contact with certain catalysts under selected conditions of temperatureunder which reactions occur which produc-e pronounced Vincreases in the oxidation stability of .the oil. The catalyst promotes reactions in which thestructures Voi the lubricating oil molecules which are .relatively unstable to oxidation .are modified to more stable structures, structures which inhibit the oxidation of a lubricating oil, or to structures which may readily be removed from the oilA by simple means such as distillation. The lubricating oil as a whole is rendered more oxidation -stableby thetreatment. While it is diilcult to determine the-exactnature ofthe reactions occurring in the treatment it appears that in general there is some increase in both aromaticity and paraffnicity apparently at the expense of naphthenic rings.

The catalysts which produce the increase in oxidation stability comprise certain composites of silica and alumina and `include generally the activable clays, particularly the non-swelling, acidtreated montmorillinite or y:bentonitic clays. Industrial activated clays which 'have been found particularly effective 'for the practice of the invention are Super Filtroland Lena Clay, each oi which is anon-swelling, acid-*treated bentonitic clay.

In accomplishing the improvement in oxidation stability the lubricating stock is contacted with the Acatalyst in pulverulent, comminuted or kpovvdered form at temperatures upwards of 600 F. and 'generally Within a range of about i550-'725 F. with a time of reaction of about one-half Aan hour up to one or .two hours. AAs the temperature is increased above' 600 F. thereactions catalyzed by the catalyst become very .active. While the extent of improvement in oxidation stability increases Ygenerally ,as the .temperature of treatment 'is raised we have 'found that there is .ai-critical temperature for each stock beyond which -a small increase in temperature results in very greatly increased stability. These fcritical temperatures are found .to .be within .the range .of about, B25-675 F, `In vreference tothe upperlimit of temperature it maybe stated that it is advisa- ApplicationMay 4, 1945, Serial No.1592305'4 ble to-employ temperatures suiciently low'that the oil being treatedmayremain `substantially in the liquid'pha-se. If Vthe 'temperature is unduly increased, coking is vapt rtO-.occur and mechanical diculties suchasaftendencyfor the 'catalyst .to settle out maybe encountered. Moreover asfthe temperature .isincreased .there is a greater danger of liavingthermal :cracking at'the expense of the desired selective -catalytic conversion. In View of these considerations the upper `limit-of temperature is labout 750 F. and vgenerally for all'stocks a temperature of about 650 F. lto 725 is the most-satisfactory. The fcontact ytime preferably approximates one -half an hour to one hour. The response -o paralnic stocks tothe catalytic treatment is better'than the response of naph-tlienic stocks.

In practicing Ythe invention thermal cracking is avoided andthe conditions of the catalytic conversion are restricted `so as to avoid any material conversion into low boiling products such as gasoline. vIn the conversion reactions inwhich a pronounced increase in 'oxidation stability 4is accomplished rthere will be a certain amount of conversion'into products of lower viscosity than that oi" the'starting material. Thus in treating a lubricating stock, of say 50G/100 F. Saybolt Universal viscosity, sufficiently to obtain .an l.adequate increase .in oxidation stability there .will be .formed some quantities of lighter `Viscosity lubricating oil and smaller proportions .of oil of the character of gasoil or-possiblyfkerosene. We have found however that by means of our process Aitispossible to obtain satisfactory increases in oxidation stability .with yields .around (i5-80% of ,product of the same viscosity as'thatof the oil treated.

The invention is particularly adapted for the treatment of refined lubricating stocks to effect the improvement in oxidation stability. 'In vthe treatment of oils for .certain purposes We have found that the sequence in which the catalytic treatment is VVapplied in .respect to other refining steps is of a .critical nature. Thus inthe production ,of turbineoils, which are required to have a high oxidation stability and alsomust be :resistant-to emulsion ror must .readily separate from emulsions which may be :produced in `the `use of theoil, it is necessary that the catalytic treatment .be applied after `the oil has been subjected to rening treatments, such as acid treatment and solventrening. We have found that, if the oil, after being given the catalytic treatment, be subjected to after-treatments such ras .sulfuric acid treating, :solvent refining, caustic washing and similar treatments, While the emulsion characteristics of the oil may be improved the aftertreating tends to greatly reduce the oxidation stability imparted to the oil by the catalytic treatment. Accordingly in the production of an oil which will have both high oxidation stability and good emulsion characteristics it is critical that the catalytic treatment for improvement in oxidation stability follow the other rening treatments. The catalytically treated oil may, however, be subjected to ltration through clay or fullers earth at moderate temperature for improvement in color Without impairing its quality for turbine oil.

In describing the invention in detail reference is made to the drawings which illustrate typical results obtainable by the inventionand wherein:

Fig. 1 is a graph showing the eiect of temperature in improving the voxidation stability test life of the oil.

Fig, 2 is a graph showing the eiect of different amounts of catalyst in electing the improvement in oxidation stability.

Fig. 3 is a graph showing the relation between yield of product and oxidation stability improvement when using different amounts of catalyst.

Fig. 4 is a graph showing a comparison of a catalytically treated oil and an inhibited oil.

Fig. 5 is a graph showing the effect of inhibiting the catalytically treated oil.

In obtaining the data plotted in Fig 1 a naphrthenic pale oil `stock having a Saybolt Universal viscosity of 500/100 F. was treated with 10% by weight of Super Filtrol. The temperatures of the treatments are plottedagainst the oxidation test life in hours of the recovered produ-ct of 500/100 F. viscosity, as determined by the A. S. T. M. turbine oil oxidation test. The test life is expressed as the number of hours required for the oil to reach a neutralization number of 2. Curve A represents the results obtained with a contact time of 63 minutes and curve B represents the results obtained with a contact time of 32 minutes. It will be seen that `for each curve there is a critical temperature beyond which a small increase in temperature results in greatly increased stability, this temperature approximating 650 F. for curve A and approximating 665 F. for curve B, which indicates that to obtain optimum results the temperature applied should approximate these temperatures or exceed them. The optimum operating temperature for this stock is about 710 lit-730 F. with 32 minutes contact time and about 685 F.-710 F. with 63 minutes contact time.

In obtaining the data plotted in Fig. 2 the 500 Pale Oil was subjected to catalytic treatment in contact with Super Filtrol at a temperature of 700 F. with 32 minutes contact time and'with varying amounts of catalyst. In the drawing the percentages by weight of catalyst are plotted against the oxidation test life in hours of the products having the same viscosity as that of the oil treated. It will be seen that from a point approximating 8-10% of catalyst the curve rises very steeply. Practical considerations involved in handling the mixture of oil and catalyst will generally place the upper limit of catalyst at around It may be stated that variations in the proportion of catalyst produce the best oxidation stability improvement for the smallest decrease in yield, the varying of the clay dosage being superior in this respect to variations in temperature or in contact time.

In the runs furnished the data for Fig. 3 the 500 Pale Stock was treated with Super Filtrol at '710 F. and 32 minutes contact time using varying proportions of the catalyst. In the graph the yield of treated oil of 500 viscosity is plotted against the oxidation test life. The different percentages of catalyst used namely, 21/2%, 5%, 10%, 15% and 20% are indicated on the curve.

In a typical example, the invention was applied to the treatment of a lubricating distillate from a Gulf Coast naphthene base crude. The distillate from the crude stills was rerun with caustic soda in vacuum distillation, a 500 Pale Oil stock being taken as one of the fractions. The Pale Oil distillate was solvent rened with liquid sulfur dioxide and then treated with sulfuric acid and neutralized. The treated product of 500 viscosity constituted a high grade lubricating oil having for example the emulsion characteristics required for turbine oils; the A. S. T. M. oxidation test life of the oil was '75. This oil was `contacted with Super Filtrol in a quantity amounting to 15% by weight of oil treated at a temperature of 665 F. and .with a contact time of 32 minutes. The treated oil was cooled and the catalyst separated. The oil was vacuum distilled to remove the lower boiling components and produce a stripped product of 506 viscosity which constituted 65.7% of the oil which had been subjected to the catalytic treating. The product had an A. S. T. M. Oxidation stability test life of 1560 hours. The overhead from the vacuum distillation was redistilled under vacuum to fractionate it into light lubricating oil, gas oil and kerosene (the latter having an initial boiling point of 406 F. and a 10% point of 422 FJ. The oil occluded on the used catalyst was recovered, obtaining an additional quantity of 500 viscosity oil as Well as some light lubricating oil, gas oil and kerosene. The oxidation test life of the recovered 500 viscosity oil was 1100 Kerosene The catalytic treatmentdid not impair the emulsion characteristics of the oil so that the product was suitable for a high gradevturbine oil.

In a second example, the invention was applied to the treatment of a parainic stock. A paran base crude was subjected to vacuum distillation and a distillate cut was acid treated and neutralized and then dewaxed by pressing. The pressed distillate was redistilled over Caustic soda and a distillate thus obtained was acid treated, then solvent refined with liquid sulfur dioxide and iinally .subjected to anti-gravity filtration through fullers earth. The treated product which had a viscosity oi /100 F. was contacted by 10% by weight of ySuper Filtrol at a temperature of 650 F. for a period of 45 minutes. The product, stripped of light ends to 154 viscosity, was subjected to the A. S. T. M. oxidation stability test and at the end of 1336 hours the neutralization number was only 1.28. The emulsion test was satisfactory for turbine oil.

In another run with a paraflinic stock a parafinic pale oil of 145 viscosity was obtained from a parailln base crude in the same manner as that of the preceding pale oil stock. The oil was acid treated, neutralized and dewaxed by pressing, the pressed distillate wasv rerun over caustic and treated with sulfuric acid and neutralized. This oil was contacted with Super Filtrol in a quantity amounting to by weight of the oil treated at a-temperature of 650 F. and with a contact -time of 32 minutes yielding a 4product of 145 viscosity amounting to 76% of the oil treated and having an A. S. T. M. oxidation stability test life of over 3024 hours. The oil satisfactorily met the emulsion tests for turbine oil.

In order to obtain the best results with the catalyst it should be dried at moderate temperatures prior to use. It is recommended that the clay catalyst be dried at temperatures of about G-400 F. at which temperature `the free water Will be driven off while the Water of combination will remain. Clay dried at these moderate temtion of an oxidation inhibitor to the catalytically treated oil. We have found that the catalytically treated product of improved oxidation stability is capable of further improvement in this respect by the addition of an inhibitor and that the cornbination of the catalytic treating and inhibiting .3

produces a product which not only possesses increased oxidation stability but also produces a product the oxidation stability curve of which exhibits a long induction period characteristic of an inhibited product and the relatively gradual :s

increase in acidity beyond the induction period characteristic of the curve of the catalytically treatedproduct.

When inhibiting the product of the catalytic treatment various agents adapted to retard oxit dation may be used. Among the materials adapted to function as oxidation inhibitors are: aromatic hydroxy compounds, such as the alkylated phenols, sulfur-containing organic compounds, such as phenol suldes, thiocarbamate compounds and sulfurized oil compounds, and aromatic amino compounds, such as tetramethyldiamino-diphenylmethane, phenylalphanapthylamine and diphenylarnine.

Figs. 4 and 5 show the eiect of inhibiting the catalytically treated product. In Fig. 4 the oxidation test life in hours is plotted against the neutralization number. Curve D is a typical curve of an inhibited turbine oil which had not received the catalytic treatment. The oil tested was a 500 viscosity oil, from a naphthene base crude, which had been solvent refined with liquid sulfur dioxide, acid treated, neutralized and ltered through fullers earth. The oil Was inhibited with tetramethyldiamino-diphenylmethane. It will be observed that the oil had a long induction period of some 900 hours after which the acidity increased very rapidly reaching a neutralization number of 2 at the end of about 1200 hours. In obtaining the data for curve C the same stock as that used for curve D was, following the filtering step, subjected to the catalytic treatment as described herein. No inhibitor was added to the catalytically treated oil. The resulting curve is typical of the catalyticalls treated product. It will be observed that the catalytically treated product had a relatively short induction period of about 250 hours and that after the induction period the rate of development of acidity was gradual being approximately linear with time. The curve of Fig. 5 is based on the catalytically treated product of curve C to which tetramethyldiamino-diphenylmethane has been ladded as an inhibitor. From the curve of the catalytically treated and inhibited oi1 it win be seen that the induction period has by the Curve D .0088 Curve C .0016 Curve of Fig. 5 .00044 Thus the rate of increase in neutralization number beyond the induction period for the catalytically treated oil (curve C) is about 1/5 of the rate for the merely inhibited oil (curve D) and the rate for the oatalytically treated and inhibited oil (Fig. 5 curve) is only about 1/zo 0f the rate for the merely inhibited oil.

When using the inhibitor it is sometimes desirable to subject the oil to moderate catalytic treatment, short of maximum oxidation stability improvement, thus reducing the treating loss to .a minimum and then to add the inhibitor to the moderately improved oil. Thus for example a refined paranic lubricating oil of 82 A. S. T. M.

oxidation stability test Was treated with Super Filtrol at a temperature of 600 F. for a period of three-quarters of an hour to yield a product of 480 A. S. T. M. oxidation stability test and a refined naphthenic lubricating oil of hours oxidation stability was treated with the same catalyst and under the same conditions to produce av product of 500 hours oxidation stability. Both of these products were inhibited with 0.03% oxidized wax and 0.1% tetramethyldiamino-diphenylmethane. The inhibited products had oxidation stability tests of 990 hours and 1050 hours, respectively.

In practicing the invention the oil and catalyst may be subjected to reaction in various types of apparatus. However a preferred operation is to pass a mixture of oil and catalyst through a care- Y fully regulated heating coil and to either quench the effluent or to pass it through a cooler adapted for rapid cooling, so as to thus accurately control the time of reaction. It is preferred to add the catalyst to the oil with the oil at normal temperature or at least after only moderate preheating so as to eliminate the effect of any strictly thermal reaction.

The oil product is fractionated to separate it into the fractions desired. For example, in one method of operation contemplated by the invention the catalytic treatment may be applied to a relatively high viscosity stock such as 750/ F. viscosity pale oil and the product fractionated to obtain a 500 viscosity oil suitable for turbine oil.

Although a preferred embodiment of the invention has been described herein, it Will be under- :Menaces-f neutralizing to therebjrproduce 1a prodmmhaving: emulsionfresistantproperties adaptedf or turbine oil; fand then "contactingiitlre .solvenrefinedl and 2.8111--themanufacture ofi-turbine oils loi superrier-'emulsion resistant and'oxidati'on stability properties' the process that comprises -rstY sub'- ject'ing'ia lubricating distillate oil to treatments involving solvent reining and acid treating and neutralizing to thereby'produce a product having emulsion resistant properties'adapted for turbine oilan'd then contacting theY solvent-refined* and acidl't'reate'dv'and neutralizedfoil with activated clayl'fin Ha `4quantity amounting to `not fless" than about 101% byweight ofthe -oil treated 'with a contact timfei'within'the range of about '1/2-1 hour atatemperature within a range from a minimum of-6'50P'Ffor a contact time'of 1 hour and from a miniinunrfof665"1F.A for a Contact time-of 1/2 hour upff'toa maximum of about 4750 Fjto thereby ef'ct reactions 'involvingan increase-in aroma* ticityfan'd formation of structures which inhibitV oxidationand' causing increased oxidation stabiliftf'llwithout'iirnpairing the emulsion resistantY propertyto Athereby produce va nislied product having-both the emulsionresistant and oxidationlistabili-ty properties. adapted for turbine oil.r

3...Iri1the';manufacture of -turbineY oils of superior-emulsion resistant and oxidation stability properties-'the process that'com-prisesfrst subjecting a lubricating distillate oil to treatments involving solvent lrening and acid treatingand neutralizing. toiiproduce-an oil of a elven viscosity and having; emulsion resistant'properties-adapted forfturloine oil',A then"v treating the solvent-rened anthracid-treatednand.neutralized oil witliacti vatedselaysina quantity amounting@ to -'not'less thai-rr aboutrl0% by' Weight of the oiltreatedat a of ...-aboutl/geflv hour:V to thereby'veiect reactionsY involving;=an7 'increase' in 1 aromaticity' `and forma'- tionroffstructuresf which inhibit foxidationff and causing ,increased oxidation stabilitir 'Withoutzim-.= pairing the Yemulsion resistant property and .dis-I tillingvoff from :thefresultantfproduct 'lowerboil-- ing constituents to obtain asresidueV a finished 21 product of y approximately th'elsame viscosity-asf. the oil .before the claycontacting and-having both :l the emulsion resistant and oxidation-stability? properties adapted forlturbine oil."

4. 'In the. manufacture of turbine oils oftsuperi'or vemulsion 'resistant and oxidation Astability properties fromtplubrcating distillate obtained.' from'fparain base crude thezprocess thatfcom# prises. .subjecting the paraiinllubricating. distil-' late to dewaxing, subjecting it to acid treating'and,` neutralizing both` .before and afterthe dewaxing'. and: then @contacting :the Y dewaxed and "doubleA acid-treatedand `neutralized 'oil .with activated clay in a quantitytamounting' to not :les's than i about"10% byweighttof the oiltreated at a temperatureof G50-750"F, `with Va contact time of' about Y1/g1 hour to thereby eiect reactions inl: volving an" increase in 'aromaticity and formations. of structures whichiinhibit :'oXidation'and-'caus-- ing increased .oxidaticnfustability Without impairfing the emulsion' resistant propertyl'and produce a finished product having both emulsionresistan'tf, and oxidation Ystability properties vadapted fortur- 'i bine oil';

FRED. C... "IOE'IFICHERI'` JOHN R. COLEY,VAVV` REFERENCES CITED The following references are of recordfin'the' file of'tliis patent:

UNITED 'STATES' PATENTS Number Name v Date 1,547,682 Puitzman July 28,` 1925 1,655,175 Benjamin' Jan.'3," 1928 1,7665338 Y Johnston June'24, 1930" 1,786,493' Isorn et al. Dec. 30,1930' 1,813,6287- Lovvery'et al. July l'7, '1931' 1,856,934 Stafford May 3, 1932 1,884,587 Darlington Oct. 25, 193'2 1,898,163 Belden Feb,21,A 1933 1,970,796 Beisvvengerl Aug.r 21; 1934" 2,222,475 Brandt Nov. 19, 1940" 2,273,147 Schumacher etal. Feb. 17, 1942 2,340,947 Evans et al. Feb. 8,1944 l 2,341,874 Lovell Feb.` 15, '19442 2,356,952 Smith Aug. v29, 1944'V 2,420,108".- Strathford et al; May 6, 19'47"" 

